Background Implant-based breast reconstruction (IBBR) remains the standard and most popular option for women undergoing breast reconstruction after mastectomy worldwide. Recently, prepectoral IBBR has resurged in popularity, despite limited data comparing prepectoral with subpectoral IBBR. Methods A systematic search of PubMed and Cochrane Library from January 1, 2011 to December 31, 2021, was performed following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) reporting guidelines, data were extracted by independent reviewers. Studies that compared prepectoral with subpectoral IBBR for breast cancer were included. Results Overall, 15 studies with 3,101 patients were included in this meta-analysis. Our results showed that patients receiving prepectoral IBBR experienced fewer capsular contractures (odds ratio [OR], 0.54; 95% confidence interval [CI], 0.32–0.92; P = 0.02), animation deformity (OR, 0.02; 95% CI, 0.00–0.25; P = 0.002), and prosthesis failure (OR, 0.58; 95% CI, 0.42–0.80; P = 0.001). There was no significant difference between prepectoral and subpectoral IBBR in overall complications (OR, 0.83; 95% CI, 0.64–1.09; P = 0.19), seroma (OR, 1.21; 95% CI, 0.59-2.51; P = 0.60), hematoma (OR, 0.76; 95% CI, 0.49–1.18; P = 0.22), infection (OR, 0.87; 95% CI, 0.63–1.20; P = 0.39), skin flap necrosis (OR, 0.70; 95% CI, 0.45–1.08; P = 0.11), and recurrence (OR, 1.31; 95% CI, 0.52–3.39; P = 0.55). Similarly, no significant difference was found in Breast-Q scores between the prepectoral and subpectoral IBBR groups. Conclusions The results of our systematic review and meta-analysis demonstrated that prepectoral, implant-based, breast reconstruction is a safe modality and has similar outcomes with significantly lower rates of capsular contracture, prosthesis failure, and animation deformity compared with subpectoral, implant-based, breast reconstruction.

Introduction Recent data suggest that margins ≥2 mm after breast-conserving surgery may improve local control in invasive breast cancer (BC). By allowing large resection volumes, oncoplastic breast-conserving surgery (OBCII; Clough level II/Tübingen 5-6) may achieve better local control than conventional breast conserving surgery (BCS; Tübingen 1-2) or oncoplastic breast conservation with low resection volumes (OBCI; Clough level I/Tübingen 3-4). Methods Data from consecutive high-risk BC patients treated in 15 centers from the Oncoplastic Breast Consortium (OPBC) network, between January 2010 and December 2013, were retrospectively reviewed. Results A total of 3,177 women were included, 30% of whom were treated with OBC (OBCI n = 663; OBCII n = 297). The BCS/OBCI group had significantly smaller tumors and smaller resection margins compared with OBCII (pT1: 50% vs. 37%, p = 0.002; proportion with margin <1 mm: 17% vs. 6%, p < 0.001). There were significantly more re-excisions due to R1 (“ink on tumor”) in the BCS/OBCI compared with the OBCII group (11% vs. 7%, p = 0.049). Univariate and multivariable regression analysis adjusted for tumor biology, tumor size, radiotherapy, and systemic treatment demonstrated no differences in local, regional, or distant recurrence-free or overall survival between the two groups. Conclusions Large resection volumes in oncoplastic surgery increases the distance from cancer cells to the margin of the specimen and reduces reexcision rates significantly. With OBCII larger tumors are resected with similar local, regional and distant recurrence-free as well as overall survival rates as BCS/OBCI.

Background: Data on the oncologic safety of omission of axillary lymph node dissection (ALND) in node positive (N+) patients who downstage to ypN0 with neoadjuvant chemotherapy (NAC) is sparse. Additionally, there is no consensus on which axillary staging procedure should be used in this setting, sentinel lymph node biopsy (SLNB) alone or in combination with localization and retrieval of the clipped positive node, also known as targeted axillary dissection (TAD). Whether the reduction in the false negative rate observed with TAD translates into a significant reduction in the rate of axillary recurrence is unknown. We sought to evaluate oncologic outcomes after omission of ALND in a large, real-world cohort of breast cancer (BC) patients and to compare rates of axillary recurrence after SLNB with dual tracer mapping vs. TAD. Methods: Data were collected from 19 centers in the Oncoplastic Breast Consortium (OPBC) and EUBREAST networks. Patients with T1-4 biopsy-proven N1-3 BC who underwent NAC followed by axillary staging with either SLNB with dual tracer mapping or TAD and who were pathologically node negative (ypN0) were included. ypN0 was defined as the absence of any tumor or isolated tumor cells. Competing risk analysis was performed to assess the cumulative incidence rates of axillary recurrence, locoregional recurrence, and any invasive (locoregional or distant) recurrence. Two-year cumulative incidence rates were compared between TAD and SLNB using the Gray’s test. Type I error rate was set to 0.05 (α). Results: We included 785 patients (565 treated with SLNB and 220 with TAD) treated with NAC followed by surgery from 01/2014-12/2020. Median patient age was 50 years. The majority (57%) of patients had clinical T2 tumors, and 95% had N1 disease. Most (55%) were HER2+, and 21% were triple negative. Most patients (81%) received anthracycline and taxane-based chemotherapy regimens, but NAC regimens differed between patients treated with TAD and those treated with SLNB (Table 1). All patients with HER2+ tumors received anti HER2 therapy. Nodal radiotherapy was administered to 76% of patients, and was more common in patients who underwent TAD (82% TAD vs 74% SLNB, p=0.017). Breast pathologic complete response (ypT0/is) was more frequent among those patients that had TAD (80% TAD vs. 66% SLNB, p&lt; 0.001). TAD localization was with wire in 46%, radioactive seed in 40%, ultrasound in 5%, tattoo in 2%, and with a combination of these techniques in 7%. The clipped node was successfully retrieved in 94% of TAD cases. The median number of lymph nodes removed was lower in the TAD group compared to the SLNB group [3 (IQR 3-5) vs 4 IQR 3-5), p&lt; 0.001], as was the median number of sentinel lymph nodes [3 (IQR 2-4) vs 4 IQR 3-5), p&lt; 0.001] (Table 1). The 5-year rates of any axillary recurrence, locoregional recurrence, and any invasive recurrence in the entire cohort were 1.1% (95%CI 0.39-2.4%), 3.1% (95%CI 1.6-5.3%) and 10% (95%CI 7.6-13%), respectively. The two-year cumulative incidence of axillary recurrence did not differ between patients treated with TAD compared to SLNB (0% vs 0.9%, p=0.19). Conclusion: Early axillary recurrence after omission of ALND in patients who successfully downstage from N+ to ypN0 with NAC is a rare event following both SLNB or TAD, and was not significantly lower in TAD than SLNB. Although longer follow-up is needed to confirm these findings, the main advantage of TAD seems to be a reduction in the number of lymph nodes removed. Overall, these results support omission of ALND in patients who successfully downstage to node negative disease after NAC. Table 1: Clinicopathological Features of the Study Cohort, Stratified by Axillary Staging Technique Citation Format: Giacomo Montagna, Mary Mrdutt, Astrid Botty, Andrea V. Barrio, Varadan Sevilimedu, Judy C. Boughey, Tanya L. Hoskin, Laura H. Rosenberger, E Shelley Hwang, Abigail Ingham, Bärbel Papassotiropoulos, Bich Doan Nguyen-Sträuli, Christian Kurzeder, Danilo Diaz Aybar, Denise Vorburger, Dieter Michael Matlac, Edvin Ostapenko, Fabian Riedel, Florian Fitzal, Francesco Meani, Franziska Fick, Jacqueline Sagasser, Jörg Heil, Konstantin J. Dedes, Laszlo Romics, Maggie Banys-Paluchowski, Maria Del Rosario Cueva Perez, Marcelo Chavez Diaz, Martin Heidinger, Mathias K. Fehr, Mattea Reinisch, Nadia Maggi, Nicola Rocco, Nina Ditsch, Oreste Davide Gentilini, Regis Resende Paulinelli, Sebastian Sole Zarhi, Sherko Küemmel, Simona Bruzas, Simona Di Lascio, Tamara Parissenti, Uwe Güth, Valentina Ovalle, Christoph Tausch, Monica Morrow, Thorsten Kühn, Walter P. Weber. Oncological Outcomes Following Omission of Axillary Lymph Node Dissection in Node Positive Patients Downstaging To Node Negative with Neoadjuvant Chemotherapy: the OPBC-04/EUBREAST-06/OMA study [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr GS4-02.

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Prepectoral versus subpectoral implant-based breast reconstruction: A systemic review and meta-analysis. Edvin Ostapenko, MD1,2, Larissa Nixdorf, MD1, Yelena Devyatko, MD1, Ruth Exner, MD1, Kerstin Wimmer, MD1, Florian Fitzal, MD1 1Department of General Surgery and Breast Health Center, Medical University of Vienna, Vienna, Austria. 2Faculty of Medicine, Vilnius University, Vilnius, Lithuania Abstract Background Implant-based breast reconstruction (IBBR) is still standard and most popular option for women undergoing breast reconstruction after mastectomy worldwide. Recently, prepectoral IBBR has resurged in popularity, despite limited data comparing prepectoral with subpectoral IBBR. Methods A systematic search of PubMed and Cochrane Library from January 1, 2011, to December 31, 2021, was performed following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) reporting guideline, data were extracted by independent reviewers. Random and fixed-effect models were applied to obtain pooled proportions and 95% CIs. The Risk of Bias in Nonrandomized Studies- of Interventions (ROBINS-I) tool was used for critical appraisal of cohorts and funnels plots, and the Egger bias test were used for evaluating the publication bias. Studies that compared prepectoral IBBR with subpectoral IBBR for breast cancer were included. Results Overall, 15 studies with 3101 patients were included in this meta-analysis. Our results showed that patients receiving prepectoral IBBR experienced fewer capsular contracture (odds ratio [OR], 0.54; 95% CI, 0.32-0.92; P=.02), animation deformity (OR, 0.02; 95% CI, 0.00-0.25; P=.002), and prosthesis failure (OR, 0.58; 95% CI, 0.42-0.80; P=.001). There was no significant difference between prepectoral and subpectoral IBBR in overall complications (OR, 0.83; 95% CI, 0.64-1.09; P=.19), seroma (OR, 1.21; 95% CI, 0.59-2.51; P=.60), hematoma (OR, 0.76 95% CI, 0.49-1.18; P=.22), infection (OR, 0.87; 95% CI, 0.63-1.20; P=.39), skin flap necrosis (OR, 0.70 95% CI, 0.45-1.08; P=.11), and recurrence (OR, 1.31; 95% CI, 0.52-3.39; P=.55). Similarly, no significant difference was found in Breast-Q scores between prepectoral and subpectoral IBBR groups. Conclusion The results of our systematic review and meta-analysis demonstrated that prepectoral implant-based breast reconstruction is a safe modality and have similar outcomes with significantly lower rates of capsular contracture, prosthesis failure and animation deformity compared to subpectoral implant-based breast reconstruction. Future research should include randomized clinical trials or well-designed prospective matched studies with adequate follow-up to assess long-term as well as oncologic outcomes between comparative groups. Key Words: immediate implant-based breast reconstruction, breast cancer, outcomes, prepectoral, subpectoral; Citation Format: Edvin Ostapenko, Larissa Nixdorf, Yelena Devyatko, Kerstin Wimmer, Ruth Exner, Florian Fitzal. Prepectoral versus subpectoral implant-based breast reconstruction: A systemic review and meta-analysis. [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-15-05.